The invention relates to apparatus for the measurement of compressive loads, and particularly, though not exclusively, for measuring the "diametral load to close" of a gapped piston ring or sealing ring.
One type of piston ring or sealing ring for which the apparatus may be used is a ring which has a small gap so that, in its free state, it has a larger diameter than that of the cylinder with which the piston to which it is fitted in use co-operates. In use, it is fitted onto the piston and then compressed (so as at least partially to close its gap) to enable it to be fitted into the co-operating cylinder. As is known in the art, the "diametral load to close", as applied to such a ring, is the compressive load which must be applied to the ring, at points respectively located at opposite ends of a diameter of the ring which is substantially at right angles to the diameter of the ring passing through the gap, in order to close the gap to the same dimension which it will have when the ring is fitted in the co-operating cylinder.
For quality control purposes, it is desirable to know the diametral load to close of such a ring.
Hitherto, there has been no standard method or apparatus for measuring the diametral load to close of such a ring, though measuring the diametral load to close of such a ring, though various forms of apparatus have been proposed. In one such form, the ring is vertically mounted near a beam which is pivoted at a point adjacent to the ring. At a point spaced from its pivot, the beam rests on the ring at one end of a diameter thereof which is substantially at right angles to the diameter through the ring gap. Outwardly of this point of contact, the beam carries a tray for receiving weights. Initially, the beam is balanced about its pivot point so that it applies zero load to the ring. Weights are then placed in the tray until the ring gap closes to the appropriate dimension, and the diametral load to close is therefore measured by the weights in the tray.
Such apparatus is cumbersome in use and sensitive to extraneous influence.
An object of the invention is to provide improved apparatus for the measurement of compressive loads.
A more specific object of the invention is to provide improved apparatus for measuring the diametral load to close of a piston ring or the like.